Akademik Veri Yönetim Sistemi
JOURNAL OF THE HELLENIC VETERINARY MEDICAL SOCIETY, cilt.75, sa.2, 2024 (SCI-Expanded, Scopus)
This study aimed to determine and compare the concentrations of progesterone, estradiol, melatonin, serotonin and nitric oxide in the blood plasma after induced estrus in and out of the natural breeding season in Tuj breed ewes. In addition, seasonal alteration in serotonin levels after induced estrus in ewes were examined for the first time. A total of 20 Tuj ewes were used in the study. The ewes were synchronized in the breeding (n=10) or non-breeding season (n=10) by using an intravaginal progestin-containing sponge (60 mg medroxy-progesterone acetate) for 12 days. Prostaglandin F2 alpha (PGF2 alpha, 2,5 ml, i.m.) plus equine chorionic gonadotropin (eCG 500 IU, i.m.) were injected at sponge withdrawal. The first blood samples were collected immediately after removal of the intravaginal sponge (at 0 hour) and the rest was collected at 4-hour intervals between 24 and 64 hours. Throughout both seasons, all animals displayed estrus. However, estrus appeared earlier in the breeding season than in the non-breeding season. Plasma progesterone, estradiol, nitric oxide and melatonin concentrations were higher ( P< 0.05) in the breeding season compared to the non-breeding season. A positive correlation was recorded between estradiol and progesterone (r=0.685; P< 0.05) or nitric oxide (r=0.535; P< 0.05). However, the plasma serotonin concentration was higher ( P< 0.05) in the non-breeding compared to breeding season and showed a positive correlation with melatonin (r=0.671; P< 0.05). In addition, significant differences were noted between day and night concentration of melatonin and serotonin hormones in both seasons ( P< 0.05). In conclusion, the results show seasonal differences in the secretion of the ovarian steroid hormones, nitric oxide, melatonin and serotonin, after induced estrus, which suggests a different reproduction capacity in the two seasons. Seasonal differences in the profile of nitric oxide release during estrus may be related to the estradiol secretion.